feat: add optional json logging format for advanced configurations

[demula]

Add extra environment variables to further configure the logrus logger in the extension.

This is very useful when the target app has to deal with different logger setups such as zerolog, zap, go-logr and others. This happens when integrating different lambda extensions and other libraries such as OpenTelemetry and the target application has zap or zerolog.

There are not significant code changes and not setting a variable will result in using the defaults previously used in the extension (logrus defaults) ensure compatibility with exiting users.

This feature enables the following setups:

• Use json as a formatter
• Skip sending timestamps as part of the log entry
• Specify the format of the timestamps
• Change default field names of logrus allowing log entries to use "ts" instead of "time" for example.

To use it, just setup the corresponding environment variables in the AWS lambda configuration and you can have logs like this ones:

{"level":"debug","msg":"Serving on 0.0.0.0:4040","svc":"pyroscope-lambda-ext-main","ts":"2023-07-18T12:47:58.318877953Z"}
{"comp":"orchestrator","level":"debug","msg":"Starting Server","svc":"pyroscope-lambda-ext-main","ts":"2023-07-18T12:47:58.31884208Z"}
{"comp":"orchestrator","level":"debug","msg":"Starting Server","svc":"pyroscope-lambda-ext-main","ts":"2023-07-18T12:47:58.31884208Z"}
{"comp":"orchestrator","level":"debug","msg":"Starting self profiler","svc":"pyroscope-lambda-ext-main","ts":"2023-07-18T12:47:58.318807397Z"}

[CLAassistant]

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[petethepig]

Thank you for the contribution @demula! I released a new version with this change: https://github.com/grafana/pyroscope-lambda-extension/releases/tag/v1.5.0.